Highly-neutralized ethylene copolymers and their use in golf balls

Abstract

Thermoplastics with high resilience (high coefficient of restitution) and softness (low Atti compressions) and their use in golf ball components. Melt-processible, highly-neutralized ethylene acid copolymers and process for making them by incorporating an aliphatic, mono-functional organic acid in the acid copolymer and then neutralizing greater than 90% of all the acid groups present.

1. A thermoplastic composition that is melt-processible consisting essentialy of a mixture of (a) at least one E/X copolymer wherein E is ethylene, X is methacrylic acid present at greater than 18 wt. % or acrylic acid present at greater than 15 wt. % and a softening monomer Y is not present and (b) one or more aliphatic, mono-functional organic acids having fewer than 36 carbon atoms or salts thereof, wherein greater than 92% of all the acid of (a) and of (b) is neutralized. 
     
     
       2. The composition of  claim 1  wherein the organic acid is selected to substantially or totally suppress the crystallinity of the E/X copolymer so that the composition is amorphous. 
     
     
       3. The composition of  claim 1  wherein about 100% of the acid in (a) an (b) is neutralized. 
     
     
       4. The composition of  claim 3  wherein an amount of cation source in excess of the amount required to neutralize 100% of the acid in (a) and (b) is used to neutralize the acid in (a) and (b). 
     
     
       5. The composition of  claim 1  wherein the organic acid is one or more C 6  to C 26  organic acids. 
     
     
       6. The composition of  claim 5  wherein the organic acid is one or more C 6  to C 18  organic acids. 
     
     
       7. The composition of  claim 6  wherein the organic acid is one or more of C 6  to C 12  organic acids. 
     
     
       8. The composition of  claim 1  wherein the thermoplastic polymer, when formed into a sphere that is 1.50 to 1.54 inches in diameter, has a coefficient of restitution of at least 0.785 measured by firing the sphere at an initial velocity of 125 feet/second against a steel plat positioned 3 feet from the point where initial velocity and velocity of rebound from the plate is determined and by dividing the rebound velocity by the initial velocity and an Atti compression of no more than 100. 
     
     
       9. A golf ball having a cover comprising the composition of  claim 1 . 
     
     
       10. A two-piece golf ball having a core comprising the composition of  claim 1 . 
     
     
       11. A three-piece golf ball having a center or inner core comprising the composition of  claim 1 . 
     
     
       12. A multi-layered golf ball wherein at least one layer comprises the composition of  claim 1 . 
     
     
       13. A one-piece golf ball comprising the composition of  claim 1 .